Earth-boring tools for forming boreholes in subterranean earth formations such as for example for hydrocarbon production, carbon dioxide sequestration, etc. generally include a plurality of cutting elements secured to a body. For example, fixed-cutter earth-boring rotary drill bits (also referred to as “drag bits”) include cutting elements that are fixed to a bit body of the drill bit. Similarly, roller cone earth-boring rotary drill bits may include cones that are mounted on bearing pins extending from legs of a bit body such that each cone is capable of rotating about the bearing pin on which it is mounted. A plurality of cutting elements may be mounted to each cone of the drill bit.
Use of drill bits having superabrasive drilling surfaces can afford improved performance in such down-hole environments. In particular, polycrystalline diamond compacts (PDCs) formed of small (e.g., micron-sized) diamond grains fused and bonded together by a high temperature, high pressure process using a metal catalyst, and supported on a ceramic substrate, can be incorporated onto a drill bit. Such drill bits have been found to provide a superabrasive abrasive surface which is capable of cutting through hard rock for extended periods of time, and under severe down-hole conditions of temperature, pressure, and corrosive down-hole environments, while maintaining the integrity and performance of the drill bit.
Polycrystalline diamond compact cutting elements in which the catalyst material remains in the diamond table are generally thermally stable up to a temperature of about 750° C., although internal stress within the cutting element may begin to develop at temperatures exceeding about 400° C. from phase changes in the metal catalyst (e.g., cobalt, which undergoes a transition from the beta-phase to the alpha-phase) and/or differences in the thermal expansion of the diamond grains and the catalyst metal at the grain boundaries. Hence, over time, such PDC drill bits are still subject to cumulative failure modes. In the course of drilling, cutting elements can wear, fracture, or accumulate damage that can alter, limit, or significantly degrade their performance in the application to which they were applied. Degradation of cutter performance can cause delays in the drilling process, increasing the overall cost of producing the well.